1. Field of the invention
The present invention relates to an airbag device that is used for protecting a vehicular occupant of a motor vehicle, in particular a type of vehicle-use airbag device installed in a steering wheel.
2. Related Art
Airbag devices employed in recent years comprise an inflator to cause generation of gas and inflation of a bag upon a vehicle collision, and an electronic control unit (hereafter known as ECU) to cause operation of the inflator in case of the vehicle collision. The ECU is conventionally located in a position separated from a steering wheel where the bag and the inflator are located in order to avoid decreasing signal detection sensitivity of a acceleration sensor installed in the ECU in case of the vehicle collision. However, this requires separate attachment procedures, and the inflator requires use of an explosive, thus resulting in the attachment procedures with poor operability. In the attachment procedures, connecting wires from the inflator are prepared in a short-circuited state with a shorting member in order to prevent an accidental operation thereof. As a result, the inflator guards against the danger of the accidental operation due to a leakage current caused by induction from the outside. When the connecting wires from the inflator are connected to the ECU during assembly of the airbag device, the shorting member which keeps the connecting wires in a short-circuited state are removed.
Thus, for the sake of improving operational efficiency during the assembly, an airbag device has been developed in which the ECU is inserted in a pad which also houses the inflator and the bag. The airbag device is installed in a cone section in the steering wheel.
An example of such an airbag device is shown in FIG. 18. In FIG. 18, an end of a cable 140 from an inflator 130 is connected electrically with a printed circuit board inside a housing of an ECU 100 with a connecter (or soldering of the end of the cable 140). When a vehicle collision has occurred, the ECU 100 sends an electrical current through cable 140 to ignite a squib of the inflator 130. Then, the inflator 130 generates gas to inflate a bag 150. With such a structure, a space must be created within a pad 180 in order to wire the cable 140 from the inflator 130 to the ECU 100, and there arises a problem that the airbag device within the pad 180 becomes quite large (thus increasing the cone depth). Also, in order to prevent accidental operation of the inflator 130 which is not connected to the ECU 100 due to electrical interference (by static electricity, etc.), a shorting member short-circuits between the terminals of the connector attached to connecting wires from the inflator 130. In such a device, the shorting member is formed inside the connector or there is another connector for short-circuiting, and thereby a complex structure for the short-circuiting is required. As a result, the connector becomes too large to be located on the board of the ECU housing, creating a larger airbag device and contributing to higher production costs.